As mobile phones, digital AV devices, IC cards and the like are highly functionalized, it is more demanded that a semiconductor silicon chip (hereafter referred to as “chip”) be highly integrated in a package by making a mounted chip smaller and thinner. In order to fulfill high integration of a chip in a package, it is necessary to reduce a thickness of a chip down to a range of 25 to 150 μm.
However, a semiconductor wafer (hereafter referred to as “wafer”) serving as a base of a chip becomes thin by grinding. Therefore, strength of the wafer decreases. This is likely to result in a crack or a warpage in the wafer. Furthermore, it is difficult to automatically carry the wafer whose strength decreases due to its smaller thickness. Therefore, it is necessary to manually carry the wafer and it is troublesome to handle the wafer.
For this reason, a wafer support system has been developed for keeping strength of a wafer by combining a plate called “supporting plate” which is composed of glass, hard plastic or the like, to a wafer to be ground, thereby preventing a crack and a warpage in the wafer. The wafer support system can keep strength of a wafer. This makes it possible to automatically carry a semiconductor wafer having been made thinner.
A wafer and a supporting plate are combined to each other with an adhesive tape, thermoplastic resin, an adhesive or the like. Then the wafer is released from the supporting plate before the wafer is diced. The wafer is released from the supporting plate as follows: in case where an adhesive tape is used for combining the wafer to the supporting plate, the wafer is ripped off from the supporting plate; in case where thermoplastic resin is used, the resin is dissolved by applying heat to the resin; in case where an adhesive is used, the adhesive is dissolved using a dissolving liquid.
For example, Japanese Unexamined Patent Application Publication No. 135272/2006 (Tokukai 2006-135272) (Published on May 25, 2006) discloses a technique for releasing a wafer from a supporting plate by adhering the wafer to the supporting plate with the use of an adhesive and dissolving the adhesive with a dissolving liquid. In the Japanese Unexamined Patent Application Publication No. 135272/2006 (Tokukai 2006-135272), a supporting plate having a through hole penetrating in a thickness direction is used. When the wafer is released from the supporting plate, the dissolving liquid is supplied to the adhesive from the supporting plate side via the through hole.
In case where the supporting plate having the through hole is used as the supporting member of the wafer as mentioned above, the dissolving liquid is supplied to the adhesive from the supporting plate side via the through hole. Therefore, the dissolving liquid permeates from the adhesive near the through hole and the dissolution advances to the wafer side. Then the wafer is released from the supporting plate by permeation of the dissolving liquid over the whole adhesive so as to dissolve the whole adhesive.
However, it takes a long time to dissolve the whole adhesive because permeation of the dissolving liquid over the whole adhesive requires much time. Moreover, it is difficult to uniformly dissolve the adhesive. As a result, it takes a long time to release the wafer from the supporting plate. This will lead to a decrease in the production efficiency. For this reason, it is desired to develop an apparatus for allowing the dissolving liquid to uniformly permeate the adhesive, with which the wafer is combined to the supporting plate, in a short time. Furthermore, with an apparatus which allows the dissolving liquid to uniformly permeate the adhesive in a short time, it is possible to remove an adhesive remaining on a surface of the wafer in a short time after the wafer is released from the supporting plate. Therefore, it is expected that the apparatus is used also as an apparatus for cleaning a wafer.